1. Field of the Invention
The invention relates to an apparatus for moving an element from a first to a second end position and vice versa and selectively keeping the element in each of these end positions, comprising an energy buffer mechanically coupled with the element, which can be in two stationary end conditions corresponding with the mated end positions wherein the energy is almost completely present in the form of potential energy, or in intermediate translation conditions, in which potential energy is transduced into kinetic energy and vice versa, a mass driven by the energy buffer, which can be moved to one of the two end positions corresponding with the end condition of the energy buffer, and locking means for the mass, in order to lock the mass in its end position.
2. The Prior Art
A similar apparatus is disclosed in U.S. Pat. No. 3,248,497. The apparatus is used for operating a vacuum switch, whereby the element drives the replaceable contact of the switch. The element consists of a rod, one end of which is fixedly coupled with the connecting portion of a fork, the teeth of which consist of flat parallel strips. The other end of the rod carries the movable contact of the switch. The fork can be replaced in its longitudinal direction with the element and the contact and together with the element and contact can be considered partly as the above-mentioned mass.
Between a spring bottom, mounted on the rod and the wall of the housing, which is traversed by the rod, there is a screw spring which, together with the bellows and the atmospheric pressure acting thereupon, exerts the function of the above-mentioned energy buffer. The screw spring, in combination with the atmospheric pressure, acts upon the bellows of a vacuum switch, dimensioned such, that when the replaceable element, i.e. the contact, the rod and the fork, is locked in one of the two outermost positions of longitudinal movement, a force always acts hereupon, driving back the contact from each of the outermost positions with equal force to the centre position. In the outermost positions a quantity of potential energy is stored either in the bellows with the atmospheric pressure acting thereupon or in the screw spring. If the lock is released in one of the outermost positions, the contact will be driven in the other direction with convertion of potential energy in the screw spring or in the bellows together with the atmospheric pressure acting thereupon into kinetic energy, which means movement of the fork, the rod and the contact, in the other direction, being the switch in direction or switch off direction, according to the foregoing position.
In this known apparatus locking the mass takes place by the means which also produces the movement of the mass. The means consist of a triangular plate which can swing in one of its angles near the free end of the fork portion and is provided with a slot traversed by a cam mounted on the fork portion. The distance from the slot to the swinging point of the triangular plate varies, so that when swinging the plate the fork portion together with the element coupled therewith is moved. The cam then runs from the one end of the slot to the other end. Locking takes place by holding the triangular plate in one of its end positions by means of electromagnetic means, in which the cam is in one of the respective slot ends.
This combination of moving means and lock means forms a relatively heavy and large assembly, whereas relatively much electric power is necessary for the operation.